I was driving my truck all morning, never skipped a beat. Mostly highway driving today. I get to a stop light and I say to myself..."Who has that loud *** bass?!" Seeing it as my whole truck was shaking. Well I look at my tach and the RPM's are jumping around. I pullover and the damn thing sounds like its camming. I cleared the code and drove it home, now it sits in the driveway and its fine.

What was that about? The code said something about excessive exhaust something something.



Please help? 98 4six that just turned over 159k

 

What you could do is remove your EGR valve, get some brake cleaner or Throttle body cleaner spray and spray the interior of the valve. The carbon probably built up and choked the spring connecting to the diaphram inside and caused it to staul. Nothing major but just an annoyance and something to keep an eye on. I'd clean it.

 

It hasnt happened since i got it home. I pulled in the driveway and it idles just fine. I've shut if off/on every couple minutes and its fine. I even took the green hose off the top of the valve and nothing happened to the motor, still ran fine. I put my finger over that green hose and felt it pulsating, but couldnt tell if it was air sucking in or blowing out.

 

Well, it may not be directly within the EGR valve then. It could be the emission tube running down to the exhaust. Cleaning the valve will allow you access to spray the tube a bit (not much) and dissolve some of the carbon built up in there. Don't forget to spray some on a rag and wipe the port on the block as well where the EGR valve mounts. Try cleaning your IAC valve out too. That can throw the engine into a staul periodically the same way an EGR valve can. Although it would throw an different code, it's best to clean both at the same time (I just used to do it that way and always had luck). Hope it helps.

 

Small block is so much easier to me. This is the EGR correct? with the green line going to it and downtube to exhaust manifold.



Not sure where the idle air control is, could you point it out?


thank you

also- after i got the code cleared, it was still running like crap. I shut it down for 5 minutes and it was a really really hard startup. If that helps. But that was the onll time it didnt start right away

 

Yes, the EGR is the UFO in the engine
The IAC in the second picture is just left of it. 2 bolts and a cylinder shape.

They both have gaskets so just be really careful when you remove them. In the first picture, the IAC is the tallest part of the picture. It's got a plastic connection towards the end of it that you just unplug.

 

They both have gaskets I imagine? If so, I need to go get those right now, maybe borrow the neighbors Benz... thank you so much again

Wow- awesome, thanks

 

No problem....if you're careful, you don't "have" to replace them . The EGR valve will be difficult b/c it looks like it's NEVER been removed.......Make sure you WD40 those bolts and the nut on the base tube VERY well b/c it's gonna be hard to break them free. The emission tube requires a large wrench (maybe 21mm or so...not exactly sure but it's pretty big).

 

Got the IAC off and soaked it with carb cleaner. Your right, I cant get those EGR bolts off. Ima soak them and go get the gaskets. thanks man

 

no problem. Just make sure to spray and let it all air dry for a few seconds before re-installing it all. Just so you don't get puddles of cleaner in the intake

 

hit me up on AIM if you need any other pointers or help: webmancorvette


peace

 

Soaking in carb cleaner will ruin the sensor. PO402 is a popet valve fault - The EGR valve is WFO. The green line runs to the EVR that expells trapped air.

You can remove the EGR valve and work it by hand to free it up - but you sould just get a new one..

 

It has not happened again and I put quite a few miles on it. Truck might be sold on Monday anyway

 

LOL , OK . Hey if yuh ever come across any of those 400 series codes , just go here for a quick run down on what they mean (A+ illustrations as well) -

http://www.fordscorpio.co.uk/egrmonitor.htm

 

thank you both so much!